[40] Photoprotection of skin against ultraviolet a damage

Publisher Summary Changes in lifestyle and the development of leisure activities and holiday habits have led to an increase in daily exposure of the skin to ultraviolet (UV) light, affecting an ever larger section of the population. At the same time, sun protective products have undergone improvements in their ability to protect skin against sunburn as reflected by continuous increases in sun protection factors (SPF). Though there is a plethora of end points related to UVB damage, most of them being directly or indirectly linked to DNA damage, there are only few specific UVA-related phenomena in the skin that can be quantified. In the field of photoprotection, considerable progress was made in the investigation of UVA damage when potent filter substances with maximum absorption in the range of longer than 320 nm became available. It became clear that some subchronic to chronic skin disorders are mainly because of UVA exposure (polymorphous light eruption being a typical and frequent example). This chapter discusses those methods of quantification of the impact of UV light on the skin, which are sufficiently discriminative to distinguish between mere UVB and complete UVB + UVA photoprotection and that are of use in the assessment of the efficacy of photoprotection.